Anyone got some practical experience of these?
Is it sensible to stick them directly to the underside of (for example) wall cupboards or is it better to stick them to some aluminium profile & attach that to the cupboard? This is DIY so I don't have to worry about the customer moaning that it's not pretty.
From what I've seen, the aluminium strip cost more per metre than you would pay for 5 metres of the 5050 LED Strip lights.
There are LED strips and there are LED strips. You need to consider the power dissipation of the ones you choose. Some do need heatsinking.
I bought a 5 metre roll to make a coolant proof light for use inside a machine tool. This involved sticking three rows of them to a core of 6 mm polycarbonate rod arranged at 120 degree intervals, and then sliding the assembly into a polycarbonate tube with end seals. When I first did it I tried the lights before making the final seals, and over a period of maybe
30 mins they warmed sufficiently for the glue to soften and stick to the tube, resulting in me not being able to slide the assembly out again :) I pulled them out brutally which tore the strips, and with a new roll started again in the light of experience. The light was entirely successful, and let me stress they didn't get hot, just warm enough for the glue to migrate. The result was greatly improved lighting inside a totally enclosed CNC lathe where the environment is rather aggressive with high pressure coolant and swarf flying about.Andrew
I got some on Ebay from a Chinese supplier - 5 metres long with a kind of clear protective covering over the entire length to make them weatherproof.
I've got them stuck directly to the undersides of my kitchen cupboards and down near the plinths of my kitchen units. They work very well and don't give off any heat that I can detect. No need to attach them to anything to dissipate heat in my experience
The strip didn't stick very well to clean copper. I stuck a couple of metres of LED strip to a copper heatsink:
After 20 minutes they got rather too hot, so I put a fan out the back, and that works fine. If you don't have the strip close together like mine, they should not get hot.
It's about the heat dissipation capabilities of the enclosure. When I'm building an LED light which might have heat issues, I usually experiment first using some power resistors fixed where the LEDs will be, and measure their surface temperature increase over the room temperature, to work out the thermal resistance of the enclosure, and hence what max LED power I can put in there for some max ambient temperature.
Forced air cooling makes an enormous difference, but also stops the unit being maintenance free as it will require periodic cleaning.
Another thing you can do is reduce the LED power input as the unit reaches the max safe operating temperature. There are some LED PSUs which have that capability, and/or a variable fan output, which are used in some high power LED lights.
In my case the ambient temperature underneath the LED lights was rather high. This is what is a couple of feet under the LEDs:
I had to get cold air from elsewhere to blow on the LEDs.
Hmm.
I was intending to buy a 5 metre reel of 5050 LEDs & use in one or two awkward corners at home, but one place I had in mind was directly above the cooker hob in the caravan (wife is always complaining about the poor light there).
I can easily attach them to the underside of a wall cupboard above the hob and 12v is not a problem, but I was concerned about the sum total of heat from the cooker + the LEDs themselves. However yours[1] is a lot bigger than mine.
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